Interchangeable Lens Layout for Compact Focal Range Switching
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Solution Overview
Problem
Existing optical devices face challenges in reducing overall lens length and preventing size increase due to the need for space to accommodate internal conversion lenses and actuators, which are limited to lens-integrated cameras with prisms and strobe lights, making them unsuitable for interchangeable lenses without these components.
Innovation Solution
An optical device design that includes a first lens group moving parallel to the optical axis and a second lens group overlapping with the first group to change focal length ranges, allowing for a shorter overall lens length by withdrawing the second group and moving the first group closer to the image plane, enabling image pickup in both focal length ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a space for insertion of the internal conversion lens is always left between the master lens and the image plane, then the internal conversion lens can be inserted and withdrawn, but the overall lens length cannot be reduced
Solution Approach 1:
The patent applies dimensional change by moving the conversion lens group in a direction oblique to the optical axis rather than strictly along the optical axis. The lens group is inserted into a space formed between the master lens and the image plane by moving in an oblique direction, allowing the optical axis of the conversion lens group to intersect the optical axis of the master lens. This oblique movement enables compact lens length reduction while maintaining focal length switching capability.
2Ease of operation
If a dedicated actuator is used to move the master lens to the withdrawal position, then the internal conversion lens can be positioned, but the lens requires internal space for accommodating the actuator causing size increase
Solution Approach 1:
The patent applies multi-functionality by designing the zoom lens group to serve dual purposes: it functions as both the conversion lens for focal length range switching and as the actuator for positioning the master lens. During zooming operation, the zoom lens group moves along the optical axis, and this same movement mechanism enables the master lens to be positioned at the withdrawal position when the conversion lens is inserted. This eliminates the need for a separate dedicated actuator, reducing internal space requirements.
3Device complexity
If the master lens is fixed at substantially the same position in the optical axis direction for both focal length ranges, then the optical system is simple, but a space for insertion always needs to be left preventing length reduction
Solution Approach 1:
The patent applies dynamics by making the master lens position variable rather than fixed. The master lens can be positioned at different locations along the optical axis depending on the operational mode: at a first position when the conversion lens is inserted, and at a second position (withdrawn) when the conversion lens is not inserted. This dynamic positioning capability allows the system to maintain a compact overall length while preserving optical simplicity through controlled movement rather than complex fixed structures.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves a compact lens length by allowing image pickup in both focal length ranges, reducing size and transition time, and is applicable to interchangeable lenses without prisms or strobe lights.
Implementation Method 1
a second lens group corresponding to a second optical axis and configured to change a focal length range of an optical system from a first focal length range to a second focal length range by being disposed on the first optical axis
Data Source
AI summary
An optical device includes a first lens group corresponding to a first optical axis, and a second lens group corresponding to a second optical axis and configured to change a focal length range of an optical system from a first focal length range to a second focal length range by being disposed on the first optical axis on a side of the first lens group adjacent to an image plane. The first lens group moves toward the image plane in a first direction parallel to the first optical axis. The second lens group moves in a second direction to allow at least part of the second lens group to overlap at least part of the first lens group in the first direction, and the second optical axis withdraws from the first optical axis.